DNA Replication Flashcards
What is the reverse transcriptase enzyme?
- RNA -> DNA
- used for HIV
- exception to central dogma
What is DNA replication?
same genome split into 2 to make daughter cells
What is translation?
turning RNA script into protein
What are the condensed chromosomes
metaphase
What occurs in each G phase of DNA replication?
- G1: prepare for DNA replication; histone proteins are made
- S: synthesis; DNA replication
- G2: DNA done replicating, prepare for mitosis
- G0: cell arrest; when cell is damaged it can get repaired or undergo apoptosis
All nucleic acids grow in what direction?
5’ -> 3’
What causes DNA to be polar?
asymmetry of phosphodiester bonds
Bases are only added to what end of DNA?
3’
What is the substrate for DNA replication?
triphosphate nucleotide (ATP, GTP, etc.)
What is the role of DNA polymerase?
- phosphodiester bond formation
- fromation of H bonds b/w bases
How many H bonds are in between A-T and G-C pairing?
- A-T: 2
- G-C: 3
How many origins of replication do we have?
multiple
The leading and lagging strand both grow in what direction?
5’ -> 3’
Okazaki fragments are a part of which strand?
lagging
What is the function of helicase?
uses ATP to unwind DNA to cause supercoiling
What is the function of topoisomerase?
releases torisonal stress caused by helicase coiling
What enzyme is able to break phosphodiester bonds?
topoisomerase
Without topoisomerase, what can happen within DNA?
there can be breaks
Which polymerase self-initiate?
RNA
How does DNA polymerase get started with replication?
needs an RNA primer
What does a primase add for replication?
20 bp
What is the function of DNA ligase?
- links okazaki fragments together
- adds phosphodiester bonds
What enzymes use ATP?
- helicase
- topoisomerase
- DNA ligase
What is DNA polymerase alpha?
does 200 nucleotides after primase
What is DNA polymerase delta?
- high processtivity
- needs PCNA (clamp)
- needs RFC (clamp loader)
What enzyme destroys RNA nucleotides?
rnase
What enzyme destroys RNA primers?
rnase H
What is the decoy in replication?
- single-stranded binding protein
- DNA polymerase E
Mutations in helicase can cause what disease?
Bloom syndrome
What is ambrucin?
potent topoisomerase inhibitor used in non-small cell lung cancer treatment
What direction does exonucleolytic correction go in?
3’ -> 5’
What is the process of exonucleolytic correction?
removal of incorrect base and DNA polymerase adds correct base in 5’ -> 3’ direction
How many base pairs do we ahve in our genome?
3 x 10 ^9
What is NAP1?
a chaperone protein that facilitates the reassembly of nucleosomes
What is the function of telomerase?
- protects ends of chromosomes from exonuclease activity
- uses RNA template but is a DNA polymerase
What phase of chromosomes are used in karyotyping?
metaphase
What is FISH?
technique used to detect short segments of DNAusing fluorescent DNA probes
What are the characteristics of active retinoblastoma (Rb)?
- P16 interacts with cyclin D/CDK4
- Rb not/lightly phosphorylated so it interacts with E2F that recruits HDAC
- NO TRANSCRIPTION
What are the characteristics of inactive retinoblastoma (Rb)?
- P16 does not interact with cyclin D/CDK4
- Rb is highly phosphorylated so it does not interact with E2F that will not recruit HDAC
- TRANSCRIPTION OCCURS
What is the purpose of PCR?
to amplify DNA sequence
What polyermase does PCR use?
DNA
What are the steps in PCR?
- Separate double stranded (DS) DNA with Heat or Helicase (DS -> SS) aka doublestranded to single stranded
- Cool and Mix known primers (20-30 NT) because DNA polyermase requires a primer
- DNA Polymerase will extend the primers and W/C bp at needed area (DNA Synthesis)
- Denature/Separate Strands and Repeat
From the article “DNA Replication”, what would be the effect of drug resistant topoisomerases for cancer prognosis?
- cancer: if drugs target topoisomerase, it will stop replication -> decreasing cancer
- cytotoxic effects: chemo has harsh side effects such as GI issues & hair loss
- drug resistance: harder to treat, different forms of topoisomerase
From the article “DNA Replication”, according to Table 1, which cancer would be a best candidate for further tests?
ovarian because it has the lowest EC50
From the “Telomeres Syndrome” article, what is dyskerin?
essential component of telomerase enzyme making telomeres
From the “Telomeres Syndrome” article, what are the degenerative disorders linked to a shortened telomerase?
- idiopathic pulmonary fibrosis
- bone marrow failure
From the “Telomeres Syndrome” article, what is dyskeratosis congenita?
- linked to mutant short telomere defect
- symptoms: skin hyperpig., luekopenia, nail dystrophy
- mortality: bone marrow failure, cancer, pulmonary fibrosis
From the “Telomeres Syndrome” article, what is TERT?
- gene providing instructions for making the telomerase gene
- highest freq. in people with progressive idiopathic pulmonary fibrosis
From the “Telomeres Syndrome” article, what does each length of a telomerase mean?
- short or too long: not healthy; can lead to disease
- long: good, healthy
